Quick, Easy 3-Man Canoe Plans

Tom, floats or amas do provide extra stability but they add more drag than you will save from having a longer, narrower main hull or vaka. Been there, done that. When they are kept out of the water and just used for emergency stability there’s no drag but then they’re just dead weight and a hassle in traffic. By all means use them for training but not for racing!

Narrow flat-bottomed boats are tricky to paddle: they are very shallow draft which raises the CoG and have poor secondary stability. I doubt you will be able to paddle your design without amas n the water. It might make a good sailboat. For sailing Petros' design is neat, much lower drag but only for sailing, I don't see any way it can be paddled with dry amas and it's obviously a longer build, curvy plank developments, keel, building frame etc.

In your sketch the amas will take about 30% of the ply; if you paddle with dry amas you’ll need 70% more ply for the same displacement as a similarly shaped monohull, with the long, narrow hull and add crossbeams (akas) weight, cost and build time will be more than double.

Race boats are long, skinny, round-bottomed and paddled in a a straight line by athletes. The enemies of an underpowered flat-bottomed hard-chine boat will be turbulence around the hard chines and skin drag; both will increase with length. If your crew lacks the strength to achieve the extra hull speed of a longer boat it may actually be slower.

Don’t reject the design in post #33 (or similar designs) too quickly; it’s not as simple as it looks. The sheers come from one sheet, the bottom from another which allows you to use different thicknesses. It has a lot of volume from only 2 ply sheets with less than 5% waste. The simple marking and straight cutting lines makes for speed and favors hand sawing. To use ply more efficiently requires fancy measuring, marking and cutting that you don’t have time for and those designs do not permit chine logs, which allow use of nails to eliminate epoxy setting times. A design that uses more ply will need more marking, cutting and fastening. I admit there are far better designs out there as far as paddling is concerned, but they’re not 3-hour builds.

 

Please see imbedded dialogue above.

My design is all about chine logs, all pre-installed, quick and easy.

My main hull is two and a half sheets. It's simple construction that can be done by three

organized, practiced guys. No glue, just sealant. Lots of ring nails and a few screws.

Because of the symmetry, one cutout can be used as a template for the next.

Not so much measuring and marking.

Do you have Skype? Can we talk? I have some questions about the layout in post #33.

P.S. The build period is four hours and not part of the timed race.
The only advantage to finishing early is getting the "pole" position for starting.
Less traffic and a psychological advantage.

Material costs can not exceed $100

 

Terry,

Is this any more to your liking?

Softer chines, wider at the waterline.

Shorter cross-bar, same amas.

Still easy to build.

Fuller stern.

 

The design looks nice but it is too different from anything I have designed and built for me to provide educated comment on likely performance. I assume you drew it stern left as is the convention, and the max beam astern of midships should reduce drag, but I think the #3 paddler is going to have problems hitting the cross-piece. I couldn't build it here based on local material costs but your ply prices are a fraction of what I pay.

I would look for one of Rick Willoughby's threads for inspiration on designing narrow hulls with outriggers. Bear in mind he was interested in pedal boats so had more power/weight ratio to work with. He may provide build times someplace.

For a time-limited build I an concerned about extra time for building the floats and cross-pieces, plus the fact that each main hull plank will be made from 3 sections so there will be twice as many joints compared to a hull less than 16 ft long. There will be longer cuts, also increased marking out time if there are no straight lines in the developments.

The long skinny planks may be tricky to handle without breakage. However, because the bends are very gentle you can attach chine logs to the bottom and gunnels to the sheers before moving them. Bear in mind that, since you cannot glue the logs and wales to the top of the flat planks and wait for the glue to set, you will be nailing them on. That will mean that a log, for example, will be underneath the bottom plank, also the battens at the ply-to-ply joints will be underneath. I'm not sure how you plan to handle that; if I had the job of adding the sealant and nailing it would likely be a messy business.

Do you have data on the building facilities? Will it be outdoors on grass for example, bring your own furniture? A parking lot? Indoors with nice, long, rigid tables to build on? This will have an impact on building time and the construction methods you can reasonably employ.

 

Thanks Terry,

Yes, stern left. I've carefully measured paddling clearances on the cross-bar but appreciate your concern.

Nothing on building times that I could find on Rick's threads but I was more interested in his lines.

Interestingly enough the power to weight ratio is not that different. He was designing to cruising at ~140 watts net with burts to ~250 watts for ~225 pounds.

We are racing at ~600 watts net for ~700 pounds. Similar ratios.

I'm okay with all aspects of the build. Hard to explain but it's simpler than you percieve.

There is only one joint in the length of the hull, so it's just under 16'.

All the chine logs and batterns will be internal and pre-attached with nails, a few screws and sealant/adhesive.

As you say, not much curing time for the adhesive. I may use five minute epoxy on the battens and white glue above the waterline.

The "small" box structure should provide adequate rigidity in the hull.

Only two curves to mark out: the bottom (only half as the cut can be used as a templte for the other half) and the lower side with the same half template idea.

The 1" X 2" logs can be used to draw these curves.

A clever marking cam will trace the wider, top deck curve from the bottom one once cut. It's a tool so can brought to the build.

Same approach with the amas. I don't see your complexity with the cross bar construction, it's just an 8' 2X4.

Brand new cross-cut saws (X3) should make the cutting okay.

I believe it's grass. Saw horses and plenty of hand tools. Part of the sponsorship money (if acquired) will go to job specific hand tools, the rest to one or two prototype builds and lots of sea trials, race specific of course.

You commented earlier on hard chines being bad for drag. Do you think the hull taper an improvement?

Will it also produce some stability once making way?

If the amas are only a 1/2" submerged at rest, do you think they will plane at 6 - 8 knots?

I figure we're going to net about 200 watts per person. Close to one Hp total.

It will be interesting to see the drag curve in a tow test once complete.

P.S. A couple other thoughts I had were: breakaway amas, once off the beach and underway but I don't think there is enough inherent stability in that hull as you said Terry.

The other, hydrofoil amas. Less weight, less drag, they would provide planing lift until fully submerged at which point they'd go into max lift by self rotating to max AoA (8 degrees) until back to the surface where they would self feather to zero AoA and exit the water or at least go back into planing stabilization mode. They'd also provide a large damping effect which may really be all that is needed here...

I think it a great solution if it can be done "simply". It would be easy to sea trial...

 

I hadn’t appreciated how much the draft is, so I assumed it was longer.

I suggest you test the 5-minute epoxy on wood as I have found different brands vary wildly in effectiveness. The effect of hard chines on drag is something I read someplace: I recall the early flat-bottomed canoes I built were very draggy but also wider and shorter. On the other hand, a flat-bottomed rowboat I built was remarkably easy to push along, about 45" bottom but only 10' long with 2.5" draft; the drag relationship is obviously not obvious! A prototype will reveal all - it's not going to be expensive or time-consuming to build!

I think you’re wildly off on available power; 200 watts is about 1/4 hp. Lance Armstrong was dynamometered at 476W or 0.64 hp, that’s leg power from a drug-taking super-athlete. The average fit cyclist rider can produce only 75 watts or 1/10hp, again from the legs, although in a burst of a few seconds it can be considerably more. Top weight-lifters can achieve several horsepower for a fraction of a second but the body and legs do most of the work not the arms. The arms are more efficient users of energy than the legs, I read once, but nowhere near as strong. After some training perhaps you might manage 100W for a few minutes but that would be on a rotating rig - with a paddle you might get half of that.

One thought I have just had regarding the drag; in any normal canoe the draft is a few inches and the water level when kneeling is at a convenient height for paddling. presumably that has driven the design of paddles. In your boat the water level may may so high that you may find it interferes with paddling.

 

I have worked with many athletes and seen many research papers on output.

Rick W claims ~160 watts output for one to four hours. That equates to about ~140 net after drivetrain losses.

The average fit cyclist can produce 100 watts all day long.

We are equally or more fit (something you have no way of judging) than RW and looking at 2 minute duration not one to four hours.

Double paddles are more efficient than single but measurably less than Ricks propeller.

I am within 20% error in my numbers and will prove that to you in my tow test drag numbers once built.

Given that error, then we may even be the same power to weight ratio as RW!

Lance Armstrong, what duration? He is an endurance athlete not sprint trained. Sure, he has to sprint but you can't be strong at both depending on your short and fast twitch muscle genetics. Duration is more important in his training and would be the focus so of course his max power output is going to be lower. That's not just leg power, ~15% comes from the upper body in cycling.

Getting quite off topic here however.

Will do on the epoxy. I may just use West and mix it super hot as it will be summer and it should kick off quickly.

If we get those butt joints done early, they'll be solid by race time.

Thanks again Terry, I appreciate your input.

 

Sorry Terry, I missed responding to your waterline concern.

OC3's, Surf Skis, K1's are likely the most similar in design to my concept.

In those, of which all three of us are familiar, you sit with your butt (edit: sometimes above) BELOW the waterline.

So, sitting six inchs above may be the oddity here...

Even in a kayak which, again we all three are accomplished at, you sit below.

I'm having a hard enough time with six inchs of freeboard, I'd like to go to four and increase the spray rail around the outside of the top deck...

Simply oversizing the top deck will allow for some 90 degree redirection of anything over a one foot wave.

It'll also give a little more point of purchase to set our butts on as number three seat only has about nine inchs athwartship!

 

Some more thoughts:

You don't need as much freeboard in a narrow hull as you would in a wide one, and even less since heeling will be limited by the outriggers.

For double paddles you would want your butts a few inches below waterline; I assumed you were using single blade paddles whcih require the butt to be considerably higher.

The double paddles won't take much longer to make and they deliver more power, not double though. A single blade paddle makes better use of the strength of the torso. You may want to try different foot braces, the usual types may not work as well with the feet so much lower, or you can always raise the foot rests to seat height.

 

Mounting confusion here Terry.

The foot heights are on deck, the same as the seat heights. It's a sealed deck.

I think I'll drop the freeboard from six inchs to four.

With a spray trim surrounding the top deck, most waves should be deflected.

What little comes aboard should slide right across.

So long as they don't rip the deck up... maybe keep it down to one inch on the horizontal.

The paddles may end up a few inchs longer to make up for the ride height, time will tell.

Have you seen how much heave bounce there is in a single-blade-paddle boat during a race?

What a waste of energy.

 

Can anyone comment here on the effect of taper in the cross-section of the hull?

Will it reduce hard chine turbulence by directing the flow downward?

Will it provide lift at speed?

Obviously it provides more buoyancy near the surface than at hull depth adding to stability.

But is it worth it for the added beam?

Should I just square it up and reap the benefits of a narrower beam?

It should make six to nine knots at full power over a two minute period by three above average skill and fitness level guys.

If it can become stable enough at speed then it wont rely on the outriggers which will reduce drag if they are mounted high enough.

To taper or not taper, this is the question.

Weight is now at 625 pounds (285 kg)

16' (5m) length

Beam 10 - 12" depending...

Freeboard: 4" (0.1m)

Power ~500 - 600 watts net

Seas: calm -1' chop

Wind: 0 - 20 knots

 

I would not bother with tapering the hull, the flair will add a third time to build and will make little difference in performance. with square corner chines everything will be assembly faster and line up without trimming/adjusting.

For this kind of race the flair will not have any noticeable advantage. It will give a dryer ride and as noted with not sink as much with added weight. But you are designing for a single design load (crew plus hull weight) and you will never get a dry ride in this kind of contest.

Keep it Simple! the faster the build, the more time you will have to rest, and fine tune what you did build. Best to put your efforts into a quality paddle design, that is your "motor" a good paddle will do more for you than hull flair. I like the Aleut paddle shape, an elongated elliptical shape blade with a high aspect ratio surface. do not make the blades too large, they will slow you down. If unsure make some and go out and practice in a canoe, kayak paddles take some practice to get used to.

 

Thanks Petros.

The chines would still be square, the flats would bend slightly so no difference in build time.

Not looking for dryness or varying load capacity.

We're building a protype for practice in building and sea-trials.

I've got the paddles figured thanks.

I was wondering if the taper would add stability while making way so we have at least a chance to get the outriggers off the water...

 

One of my boats

Made a plan for a quarter of it to get the measures, made a small model and built the boat within a week -- without paint: 16kg. Is an easy and simple way to get a light and fast canoe.
Found this drawing in the net to explain the process.

 

Can anyone comment here on the effect of taper in the cross-section of the hull?

Will it reduce hard chine turbulence by directing the flow downward?

Will it provide lift at speed?

Obviously it provides more buoyancy near the surface than at hull depth adding to stability.

But is it worth it for the added beam?

Should I just square it up and reap the benefits of a narrower beam?

It should make six to nine knots at full power over a two minute period by three above average skill and fitness level guys.

If it can become stable enough at speed then it wont rely on the outriggers which will reduce drag if they are mounted high enough.

To taper or not taper, this is the question.